1. Field of the Invention
The present invention relates to a liquid electrophotographic printer, and more particularly, to an apparatus for recovering a carrier from a photoreceptor belt.
2. Description of the Related Art
An electrophotographic printer such as a laser printer or copier is divided into a dry type printer using a powdered toner, and a liquid type printer using a developer liquid in which a toner is mixed with a liquid carrier such as NORPAR commercially available from Exxon, depending on the development method used. In both types of electrophotographic printers, an electrostatic latent image formed on a photoreceptor belt is developed by supplying toner thereto, and then an image is printed via a transfer medium.
A conventional liquid electrophotographic printer shown in FIG. 1 includes a printing unit 10 for printing a predetermined image on a feed sheet 1, and a carrier recovery apparatus 20 for removing a liquid carrier from a photoreceptor belt 14 for recovery.
The printing unit 10 includes the circulating photoreceptor belt 14 supported by a multitude of guide rollers 11, 12 and 13, laser scanning units 18a, 18b, 18c and 18d for forming an electrostatic latent image on the photoreceptor belt 14, development devices 15a, 15b, 15c and 15d for developing the electrostatic latent image by supplying a toner mixed with the liquid carrier, and a transfer roller 16 for transferring the developed image to the sheet 1. Reference numeral 17 represents a charging station for charging the photoreceptor belt 14 to a predetermined level.
The structure of the carrier recovery apparatus 20 will now be described in more detail with reference to FIG. 2. Referring to FIG. 2, in a manifold 21, a drying roller 22 is provided for absorbing the liquid carrier from the photoreceptor belt 14 while rotating in contact with the photoreceptor belt 14, and heating rollers 23 are provided for heating the drying roller 22, in contact therewith, and evaporating the absorbed carrier.
The evaporated gas carrier is accommodated within the manifold 21. Since a multitude of heat exchanging fins 21a are formed on the outer surface of the manifold 21, the gas carrier is condensed on the inner surface of the manifold 21 by heat exchange. The condensed carrier is collected from the inner surface of the manifold 21 to then be induced to a cartridge 26 through a first recovery tube 25.
Also, the uncondensed gas carrier of the manifold 21 is induced to a condenser 28 along a supply line 27 by the driving of a supply fan 29. Since a liquid condensed carrier 28a is contained in the condenser 28, the induced gas carrier is liquefied by the heat exchange with the condensed carrier 28a. As the gas carrier is condensed, the surface level of the condensed carrier 28a rises. Then, some of the carrier is recovered in the cartridge 26 through a second recovery tube 31. The gas carrier which is not condensed even in the condenser 28 is filtered via a filter 30 together with the air exhausted to the outside. Reference numeral 19 represents an exhaust line connected to the outside through the filter 30, for removing moisture from the printing unit 10. Reference numerals 32 and 33 represent a drain line and a moisture reservoir, for draining moisture from the liquid carrier 28a stored in the condenser 28 and storing the same, respectively.
In the conventional carrier recovery apparatus 20, since the gas carrier which is not condensed in the condenser 28 is removed by the filter 30, the lowering of the filtering capacity of the filter 30 may effuse the unfiltered gas carrier. However, since the NORPAR used as the carrier is a hazardous pollutant material, it is necessary to prevent the carrier from being effused.